Menu Close
Lateral spinothalamic tract pathway

Pain and Temperature Pathways

(Lateral Spinothalamic Tract)


The sensory pathways that deliver pain and temperature information to the brain are each composed of a receptor and three successive neurons.

A receptor is the initial portion of the first neuron in a pathway, which is sensitive to changes in the environment (= stimuli). Pain receptors (nociceptors) and temperature receptors (thermoreceptors) are unencapsulated and branched, like the fine roots of a plant.

Because nociceptors and thermoreceptors contain no specialized structures, they are often referred to as free nerve endings. They are especially abundant in the skin but occur elsewhere in the body. Internal nociceptors are found in a variety of organs, such as the muscles, joints, bladder, gut, and digestive tract.

Neurons and Pathway

The first neuron in a pain or temperature pathway is called a sensory neuron (or first-order neuron). An axon of a sensory neuron passes through the dorsal root ganglion and extends to the dorsal horn of the spinal cord, where it synapses with a second-order neuron (or interneuron). The term interneuron applies to any neuron within the central nervous system.

First-order neuron, second-order neuron, and spinal cord

Labeled and Unlabeled Versions
(1125px X 800px)

The axon from the second-order neuron decussates (crosses) within the spinal cord and ascends in the lateral spinothalamic tract, along with other second-order neurons.

Lateral spinothalamic tract and second-order neuron

Labeled and Unlabeled Versions
(1125px X 1000px)

The spinothalamic tract axons pass through the medulla oblongata region of the brain before terminating at the thalamus’s ventral posterolateral (VPL) nucleus.

Full pain and temperature pathway, showing lateral spinothalamic tract, medulla oblongata, and brain

Labeled and Unlabeled Versions
(1125px X 1500px)

In the thalamus, the second-order neuron synapses with a third-order neuron (interneuron). The axon of the third-order neuron then carries signals to the primary somatosensory region of the cerebral cortex, where the input is imaged and interpreted.

Terms of Use

“We encourage you to use Human Bio Media’s materials for creating custom content.”

Human Bio Media materials are open-source and can be adapted and shared by anyone according to the Creative Commons Attribution 4.0 License guidelines.

creative commons

If you are redistributing Human Bio Media materials in print or digital formats, you should include on every page the following attribution:

Access this content for free at

References and Attributions

OpenStax, Anatomy and Physiology – “Central Processing.”

Access for free at

Wikipedia – “Spinothalamic Tract.”